Printing, as an industry serving humanity, provides a certain degree of pollution to the environment while providing people with a colorful life, such as production of water pollution, air pollution, and massive consumption of natural resources. At the initiative of the World Environmental Organization, the printing industry is striving to improve production conditions, save raw materials, and reduce or abandon the use of harmful chemical materials, especially gravure inks.
As one of the four major printing methods, gravure printing has always been known for its vivid and beautiful ink. The gravure printing ink consists essentially of 5% to 15% pigment, 20% to 40% binder resin, and 0 to 60% solvent. Intaglio printing inks can be classified into publishing inks, packaging inks, industrial inks, etc. At present, domestic printing inks are divided into general soft packaging (such as shopping bags, maternal and child hygiene products) ink (the ink is mainly benzene-soluble polyamide resin PA), cigarette packaging ink (based on nitrocellulose resin NC) and carton Ink (water-based ink), and more than 70% of compound inks are BOPP special inks based on chlorinated polypropylene (CLPP), 10%-20% are polyurethane (PU) inks, and some are PVBs. Alcohol soluble ink.
Gravure ink contains a large amount of volatile organic solvents (VOC), accounting for almost 50% of gravure ink composition. Among them, aromatic hydrocarbons contained in low-boiling, high-volatile solvents such as xylene, toluene, ethyl acetate, butanone are toxic and flammable, and are the main factors contaminating the environment. In addition, the gravure printing speed is extremely high, the use of extremely fast-drying ink must be used, and external drying (gravure printing with a drying process) is required to rely on electricity or infrared heating to meet the printing requirements, so the large amount of waste gas discharge makes the gravure It is particularly prominent in the environmental issues of all printing processes.
Currently used gravure printing inks are generally made of chlorinated polymers. In the ink production process, chlorinated polymers need to use a strong solvent (such as toluene and other aromatic solvents) to the solvent, and in the printing process with toluene to adjust the viscosity of the ink. Chlorinated polymer inks do not meet environmental requirements because chlorofluorocarbons that evaporate during the production of chlorinated polymer inks can damage the ozone layer. The use of aromatic solvents (toluene) can cause harm to the health and safety of workers during ink production and printing. In addition, the solvent residue in the ink is another major concern. For example, packaging printing, because toluene is a slow-drying solvent, can easily remain in the dry ink film layer, and it will contaminate the food in the package. Therefore, the development and application of benzene-free solvent inks and water-based inks are required, and the realization of solvent-free benzene-based and water-based gravure ink printing is not an option.
1. Develop and apply intaglio alcohol-soluble composite ink
Since water-based gravure inks are not yet a complete replacement for toluene inks, the ink industry has been working hard to develop alcohol-compatible inks that meet environmental requirements. The ink can solve the health problems caused by toluene ink and the influence of solvent residue on the quality of packaged food. In Europe and the United States, the development and application of alcohol-soluble composite inks has become a trend. In Asia, such as Singapore, South Korea and other countries, toluene ink is being eliminated, replaced by alcohol-soluble gravure ink. Alcohol-soluble inks are now widely used in the domestic gravure printing industry. It can be predicted that in the near future, alcohol-soluble inks will occupy a major share of the flexible packaging ink market in China and even the world.
The gravure alcohol-soluble composite ink has the characteristics of low odor, benzene-free, etc. The application of this environmentally friendly ink will inject new vitality into gravure printing.
2, gravure ink water-based
Although water-based gravure inks have attracted attention as an alternative to toluene-based inks, inks in packaging film printing are still water-based and have not yet reached a practical stage. In general, the important reason why water-based gravure inks have not been popularized further is that the printing performance and quality still do not reach the surface of solvent-based gravure inks. This is mainly due to the higher surface tension of the water, which makes it difficult to wet the ink. If you want to get gravure printing and printing quality of gravure solvent ink, not only water-based ink itself requires advanced technology, but gravure printing equipment and printing plate rollers also need to be improved. For example, changing the serving or engraving cylinder with a groove depth of about 38 to 42 microns to a laser plate making drum with a groove depth of about 24 to 28 microns requires a more effective and powerful drying equipment and a printing plate roll that must be made of corrosion-resistant materials. Components such as ink pumps and scrapers require considerable investment in these updates.
Despite difficulties, gravure printing ink production is subject to laws and regulations such as Fire Protection Law, Labor Safety Law, and Health Law. For long-term development of gravure printing, we must actively develop and apply green gravure inks and water-based inks that meet environmental protection requirements. .
Source: China Ink Network